This study examined the effects of hemispheric damage on the discrimination shift learning tasks. Three patient groups with cerebral infarction, i.e., BHD (both hemisphere damage), LHD (left hemisphere damage), and RHD (right hemisphere damage), were participated. The results showed that all of the groups could learn an intra-dimensional task (ID task) faster than an extra-dimensional task (ED task) according to achievement scores, such as total trials and total rate of errors to the learning criterion. The subproblem analyses of ED tasks, it showed the qualitative difference of learning processes in LHD. That is, the results suggested that LHD patients performed discrimination shift learning primarily by means of the S-R association learning strategy, while RHD and BHD patients performed the tasks by means of the mediational learning strategy. This finding was discussed in terms of hemisphere-specific dysfunctions, i.e., verbal mediational and attentional deficits, which could affect the discrimination shift learning tasks.

Key words: patients with brain damage, discrimination shift learning, subproblem analysis